Metals above carbon in the reactivity series
2 marks · EasyA factory uses 18,000 kWh of electricity to extract 1 tonne of aluminium by electrolysis, while producing 1 tonne of iron by reduction with carbon uses 800 kWh. Calculate how many times more electricity is used to produce 1 tonne of aluminium than 1 tonne of iron. Give your answer to the nearest whole number.
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22 times (±1)
Also accept: 22
Common mistakes: 21.5 (not rounded); 23 (rounded up instead of down)
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Marking points
M1 · 1 mark · Divides electricity used for aluminium by that used for iron (18,000 / 800).
A1 · 1 mark · Correctly calculates and rounds the answer to the nearest whole number (22).
Worked solution
Divide the electricity used for aluminium by that for iron:
Rounding to the nearest whole number: 22